Method of making heat exchanger nest and more particularly cooling radiators



. A. E. PLEGAT 3,386,52 METHOD OF MAKING HEAT EXCHANGER NEST AND MOREJune 4, 1968 m f w L um. sw .I ww

um". HMI ull llll PARTICULARLY COOLING RADIATORS Orlglnal Flled July 11963 United States Patent O 3,386,152 METHOD F MAKlNG HEAT EXCHANGERNEST AND MORE PARTCULARLY COGL- ING RADIATORS Alain Edouard Plegat,Asnieres, Seine, France, assigner to Societe Anonyme des UsinesChausson, Asnieres, Seine, France, a company of France Continuation ofapplication Ser. No. 291,719, July 1, 1963. rIhis application Aug. 17,1967, Ser. No. 661,469 Claims priority, application France, July 9,1962,

4 claims. (ci. 29-1s7.3)

ABSTRACT 0F THE DISCLOSURE Heat exchanger cores, including circulatingtubes covered with solder and secured at both ends to collectors alsocovered with solder and having collars around the holes through whichthe tubes extend and having heatdissipating fins along the length of thetubes, are manufactured by assembling the collectors and the fins on thetubes to form a unit with the collars of the collectors extending in thesame direction; the so-constructed unit is then submitted to fluxing;the soldering is then accomplished by blowing heated air over half ofthe unit and then cooling; finally, the unit is turned over and theother portion is soldered by the use of heated air and then cooled.

This application is a continuation of my application Ser. No. 291,719,filed July 1, 1963, and now abandoned.

Up till now, heat exchangers, more particularly cooling radiators, aremade in several successive soldering operations. These operations rstlyconsist of connecting a nest of tubes by soldering to a group of fins,then to mount on this nest a lower collector and an upper collector eachhaving collars closely surrounding the tubes. These collectors are thensoldered, more particularly by dipping and the assembly is cooled.

This method of manufacture consequently necessitates, between eachoperation, handling and transfers between successive machines, whichleads to relatively long work times, and hence, high cost prices for thearticles made.

The present invention obviates this disadvantage by creating a newmethod of manufacturing heat exchangers, enabling the simultaneoussoldering of the tubes to the fins and collectors of radiator nests orother exchangers.

According to the invention, a lower and upper collector, receive on atleast one of their faces, a coat of fusible material, the lowercollector is slipped on to the previously tinned tubes, placed parallel,fins and upper collector Which have, for closely surrounding thesetubes, collars directed in the threading direction, the feet of thetubes are bulged into the collars of the collectors, the nest thusformed is pickled by means of a flux, the traces of flux are partiallyeliminated, the bottom half of the nest placed vertically is heated sothat the heat exchange occurs more intensely with the lower collectorthan with the fins whose thermic inertias are different, to create aneven rise of temperature up to the threshold for which the fusiblematerial melts and connected between them, tubes, ns and lowercollector, the assembly being then cooled, then the nest is turned roundfor 180 on itself to bring the upper collector to the positionpreviously occupied by the lower collector, the tubes being againvertical, lastly, the non-soldered half of the nest is heated brought tothe lower part, in a similar manner to that having caused the liaison ofthe half already soldered, heating which is then followed by a cooling.

3,3%,152 Patented June 4, 1968 rice Various other characteristics of theinvention will moreover be revealed by the detailed description whichfollows.

Forms of embodiment of the device for putting the method according tothe invention into operation are shown, by way of non-restrictiveexamples, in the attached drawing. y

FIGURE 1 is a partial perspective, partly in section, showing one of thecharacteristic phases of the method according to the invention.

FIGURE 2 is a plane view showing diagrammatically an arrangement of thedevice for operating the method of the invention.

FIGURES 3 and 4 are diagrammatic elevations showing other arrangementsof the device.

In the method of the invention, the nest of the eX- changer is formed byassembling various constitutive elements, i.e. by the assembly of tubes,fins or other secondary exchanger elements and collectors, then theassembly is subjected to a chemical pickling. A following phase consistsof a progressive heating of one of the halves of the nest up to atemperature causing the melting of a soldering alloy ensuring theSoldering of the parts. This operation is followed by a cooling that iscontrolled and limited, and a turning round, to produce, in a similarmanner to the first half of the nest, the heating and soldering of thesecond half of this nest, then the cooling of the whole.

In a known manner, a heat exchanger comprises a considerable number offins threaded on to the tubes or spaces arranged between the tubes whoseends are engaged in an upper and lower collector inside of which theends of the tubes are spread out or bulged and on which water boxes arefitted.

According to the invention, the two collectors are provided with a coatof fusible material on at least one of their faces, for example, bydipping in a bath or by depositing a thin coat under atomized form by afluid jet under pressure. Provision can also be made to form this coatof fusible material by a perforated plate, of slight thickness, insertedbetween each collector and the contiguous fins at the moment ofassembling. The lower collector, the fins and the upper collector arethen slipped on to the tubes placed parallel. These two collectors havecollars directed in the threading direction, for closely surrounding thetubes, i.e., one of the collectors having collars projecting from theside of the nest whereas the other has collars projecting from the sideof the water box.

To ensure a correct maintaining of all the elements during successivehandlings and operations and chiey so that the circulation ofcirculation liquids can subsequently be correctly carried out, the feedof the tubes that project inside the collectors are bulged as known perse. This well known operation which may be conducted for instance asrelated and shown in French Patent 1,038,- 962 also has the effect ofobtaining a better contact between the walls both of tubes and'collars,thus enabling thin and stronger solderings to be effected.

The manufactured nest, whose fins or other indirect exchange surfacesand the tubes, are of tinned metal, is pickled by immersion in asuitable flux bath.

After immersion, the traces of flux are partially eliminated, so as onlyto retain the necessary and sufiicient quantity, by providing a drainingof the nest which is preferably conveyed to a sloping position to allowa good ow by gravity and avoid any retention by the ns or by the tubeswhich are placed in planes perpendicular in relation to each other.

After returning the nest to thevertical position, blowing takes placewhich completes the generally insufficient drainage.

The nest, still in the vertical position, is then put into a heatingoven preparing the soldering of the lower half. This lower 'half isheated so that the heat exchange occurs more intensely with thecollector than with the fins whose thermic inertias are lower.

To this end, two preheating zones or chambers may be provided withdifferent heights in which the nest is successively carried along sothat the first zone chiefly produces a rise in temperature of thecollector and that the second zone, while continuing this rise intemperature, also ensures the heating of the fins and tubes.

A single pre-heating zone may also be provided cornprising internally,either two jets of hot air at different temperature, or a single jetcomprising, according to a definite plan, burners directed towards thecollector.

Another heating zone is also provided for ensuring the regular rise intemperature of the whole up to the threshold for which the fusiblematerial melts and connects the tubes, fins and lower collectortogether.

As shown in FIGURE 1, this first soldering is advantageously performedfirstly on the lower half of the nest provided with the collector A withcollars a on the nest side, so that the melted solder tends to flow fromthe tubes B towards the collars a. It has been noticed that it wasadvantageous that the height of the ovens should be slightly greaterthan half the height of the nest, so as to obtain the covering of themiddle part and a certitude of the soldering of the fins C (shown inphantom) extending into that part. In certain cases, a blowing point maybe arranged at the exit from the soldering zone, to eliminate eventualrun-outs in the tubes B.

The assembly is then subjected to a controlled cooling, by a naturallowering of the temperature or by forced lowering, more particularly byintake of the ambient air through the nests and discharge of this airtowards the outside, to avoid during the soldering of the second half ofthe nest a rise in temperature obtained by conduction to the halfalready soldered, thereby causing a passing to the pasty or liquid stateof the fusible material, which might be likely to interfere with thequality of the solderings previously made.

The nest is then turned round for 180 on itself to bring the uppercollector A', i.e., the collector having collars a projecting on thewater box side, in the place previously occupied by the lower collectorA, the tubes B being once more in the vertical plane.

Lastly, the non-soldered half of the nest is heated at the lower part ina similar manner to that described above.

In the same manner as before, after leaving the soldering zone and theeventual passage facing the point for blowing on the run-outs, theassembly is subjected to a more or less accelerated cooling, intended toallow storage handlings and manipulations necessitated by the lastmounting operation, checking or putting under pressure to be carriedout.

FIGURE 2 shows the device for operating the method described above.

According to this example, the device comprises a conveyor 1 determininga line and progressing direction lfor the nests that it conveys towardstwo successive ovens 2 and 2a each confining a pre-heating zone 3respectively 3a and a soldering zone 4, respectively 4a.

As already explained above, each pre-heating zone may comprise a secondchamber 5 or 5a provided to compensate for the different inertias of thefins and collectors.

The device is more particularly shown in FIGURE 2, under the form of anequipment in line, but it is quite obvious that other arrangements canbe considered in function of the premises and effective surfaceavailable, for

l example, an installation in close circuit illustrated by FIG- URE 3 oran installation in staged circuit shown in FIG- URE 4.

The invention is not restricted to the forms of embodiment described indetail, for various modifications can be applied to it without goingoutside of its scope.

What is claimed is:

1. A continuous method for the manufacture of heat exchanger cores ofthe type comprising circulating tubes covered with fusible solder andsecured at both ends respectively with upper and lower collectors alsocovered with fusible solder and provided with collars around holesthrough which said tubes extend and having heat dissipating means alongthe entire length of said tubes, said method consisting essentially of:in a continuous manner providing said collectors with collars extendingin opposite directions respectively for said upper and lower collectors;assembling said solder covered collectors and heat dissipating means onsaid solder covered tubes to form a unit with the collars of saidcollectors extending in the same direction; submitting said unit to afiuxing action; submitting substantially one half of said unit includingone collector -to blowing heated air to provide a temperature to whichsaid fusible solder covering at least said tubes and collectors ismelted to effect soldering of said tubes to said heat dissipating meansand to said colector of said half unit; air cooling said solderedportion of the unit; turning said unit and then submitting the remainingportion of said unit to same blowing heated air and cooling actions.

2. A method as set forth in claim 1, wherein during said blowing ofheated air said tubes are maintained in vertical position with thecollector of said half unit at the base thereof whereby fusible solderflows towards said collector when melted.

3. A method as set forth in claim l, wherein said heating by blowing ofheated air to which each half of said unit is subjected comprisespreheating by blowing of heated air over only said collector at atemperature lower than the melting Itemperature of said fusible soldercoating, and then blowing heated air over` the whole lower half unitincluding said preheated collector until the melting ternperature ofsaid fusible solder is reached, whereby heating action is uniformizeddespite difference of thermic inertia of said collector with respect tosaid tubes and heat dissipating means.

4. A method as set forth in claim 1, wherein the unit is heated byblowing heated air at each occurrence along half of its height plus asmall extent beyond its midpoint whereby heating action is producedtwice on a zone of said unit situated at the middle part thereof.

References Cited UNITED STATES PATENTS 2,191,631 2/1940 Shutts et al113-118 2,211,813 8/1940 f Franco-Ferreira 29-157.3 2,184,658 12/1939Young 29-1573 X 2,650,420 9/1953 True 29`495 X 2,765,761 10/1956 Tiuran228-20 3,139,679 7/1964 Saj 29-471.1 2,298,996 10/1942 Woods 29-502 XFOREIGN PATENTS 929,664 6/ 1963 Great Britain. 1,219,386 5/1960 France.

CHARLIE T. MOON, Primary Examiner.

